<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>示例1</title>
    <script src="jquery.js"></script>
    <script>
        $(function (){
            $("#btn1").click(function (){
                alert("点击了")
            })
        })
    </script>
</head>
<body>
    <button id="btn1">点击</button>
</body>
</html>